This Core Support unit will continue to provide a wide variety of well- characterized cell cultures, of both vascular and non-vascular origins, to the various scientific components in the Program. Since its inception in 1978, Core A has endeavored to minimize cost duplication within the Program while providing consistently reproducible in vitro systems central to the testing of their scientific hypotheses. In addition to the application of standard culture methods (e.g., isolation of human endothelial cells from umbilical veins and their large-scale amplification in short-term culture), Core A personnel have worked with project investigators to develop new cultures, techniques, and in vitro models designed to meet the special needs of individual projects. During the past project period, this has included, for example, the production of uniform endothelial monolayers on the surface of a thick collagen gel matrix, which were essential for the in vitro, live-time, videomicroscopic model of leukocyte attachment and transmigration, developed by Dr. Luscinskas in Project 1. In the next project period, to support the major new emphasis on an integrative pathophysiology theme in the mouse, a major effort of Core A will be the isolation, propagation and characterization of murine endothelium from various tissue sources and genetic backgrounds. This will include the establishment of murine endothelial cell lines with unique features (e.g., VCAM-1 and/or ELAM-1 gene knockouts), thus facilitating their wide-spread use within this Program. It is anticipated that this will comprise a significant developmental component of this Core Unit in the renewal period.